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Reinette (Oonsie) Biggs

Forest fragmentation

Brief description

In the Brazilian Amazon, private land accounts for the majority of remaining native vegetation. Understanding how land-use change affects the composition and distribution of biodiversity in farmlands is critical for improving conservation strategies in the face of rapid agricultural expansion. Working across an area exceeding 3 million ha in the southwestern state of Rondônia, we assessed how the extent and configuration of remnant forest in replicate 10,000-ha landscapes has affected the occurrence of a suite of Amazonian mammals and birds. In each of 31 landscapes, we used field sampling and semistructured interviews with landowners to determine the presence of 28 large and medium sized mammals and birds, as well as a further 7 understory birds. We then combined results of field surveys and interviews with a probabilistic model of deforestation. We found strong evidence for a threshold response of sampled biodiversity to landscape level forest cover; landscapes with <30–40% forest cover hosted markedly fewer species. Results from field surveys and interviews yielded similar thresholds. These results imply that in partially deforested landscapes many species are susceptible to extirpation following relatively small additional reductions in forest area. In the model of deforestation by 2030 the number of 10,000-ha landscapes under a conservative threshold of 43% forest cover almost doubled, such that only 22% of landscapes would likely to be able to sustain at least 75% of the 35 focal species we sampled. Brazilian law requires rural property owners in the Amazon to retain 80% forest cover, although this is rarely achieved. Prioritizing efforts to ensure that entire landscapes, rather than individual farms, retain at least 50% forest cover may help safeguard native biodiversity in private forest reserves in the Amazon.

Bluefin tuna in West Atlantic

Brief description

Following intense overfishing in the 1970s, the western stock of Atlantic bluefin tuna (Thunnus thynnus) experienced a long period of depressed abundance, which has been attributed to failure of the population to periodically produce large numbers of juveniles, the western stock mixing with the more highly exploited eastern stock (fisheries in the Northeast Atlantic Ocean and Mediterranean Sea), and regime shift in the population's ecosystem resulting in lower replacement rates.

Ecosystem service regime shifts in China

Brief description

Poverty alleviation linked to agricultural intensification has been achieved in many regions but there is often only limited understanding of the impacts on ecological dynamics. A central need is to observe long term changes in regulating and supporting services as the basis for assessing the likelihood of sustainable agriculture or ecological collapse. We show how the analyses of 55 time-series of social, economic and ecological conditions can provide an evolutionary perspective for the modern Lower Yangtze River Basin region since the 1950s with powerful insights about the sustainability of modern ecosystem services. Increasing trends in provisioning ecosystem services within the region over the past 60 years reflect economic growth and successful poverty alleviation but are paralleled by steep losses in a range of regulating ecosystem services mainly since the 1980s. Increasing connectedness across the social and ecological domains after 1985 points to a greater uniformity in the drivers of the rural economy. Regime shifts and heightened levels of variability since the 1970s in local ecosystem services indicate progressive loss of resilience across the region. Of special concern are water quality services that have already passed critical transitions in several areas. Viewed collectively, our results suggest that the regional social–ecological system passed a tipping point in the late 1970s and is now in a transient phase heading towards a new steady state. However, the long-term relationship between economic growth and ecological degradation shows no sign of decoupling as demanded by the need to reverse an unsustainable trajectory.

Key References

Loess Plateau in China - ecosystem restoration

Brief description

This documentary demonstrates that it is possible to rehabilitate large-scale damaged ecosystems, to restore ecosystem functions in areas where they have been lost, to fundamentally improve the lives of people who have been trapped in poverty for generations and to sequester carbon naturally. This approach has been dramatically proven on the Loess Plateau in China, the highland area spanning some 640,000 square km in north central China. It is the birthplace of the Han Chinese, headwaters of The Yellow River and home to a new environmental and economic paradigm: A degraded ecosystem of more than 35,000 square km of land now teems with life and supports the sustainable economic, social and agricultural activities of its people."

Key References

The film "Hope in a Changing Climate" by John D. Liu http://vimeo.com/19661805

Key References

Settlement of Iceland

Brief description

Until the arrival of the Norse in AD 871, at the height of the Viking expansion across the North Atlantic, Iceland was a pristine wilderness. The arrival of humans and the sheep, goats, pigs and cattle they brought with them had a profound - some would say devastating - effect on the ecology of the island. Most notably, tree cover collapsed and soils were widely lost to erosion.

Summary

The Chesapeake Bay is the largest estuary in the United States, and lies off the Atlantic Ocean, surrounded by Maryland and Virginia.
The bay is mostly known for its seafood production, especially blue crabs, clams and oysters. In the middle of the twentieth century, the bay supported 9,000 full-time watermen, according to one account. Today, the body of water is less productive than it used to be because of runoff from urban areas (mostly on the Western Shore) and farms (especially on the Eastern Shore and in the Susquehanna River watershed), over-harvesting, and invasion of foreign species.
In contrast to harvesting wild oysters, oyster farming is a growing industry for the bay to help maintain the estuary's productivity as well as a natural effort for filtering impurities from the water in an effort to reduce the effects of man-made pollution.